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Hitachi Yutaki M & Yutaki S fault 7

Decrease in discharge gas superheat

Heat pump

What it means

Cycle fault: discharge gas superheat has decreased below acceptable level.

Likely causes

  1. Excessive Refrigerant Charge
  2. Failure of Thermistor
  3. Incorrect Wiring
  4. Incorrect Piping Connection
  5. Expansion Valve Locking at Opened Position (Disconnected Connector)

Where to start

  1. Check LED1 (Green) for power indication
  2. Check LED2 (Red) for power indication
  3. Check LED3 (Red) for heat pump operation (thermo ON/OFF) status

The full answer, free

  • 3 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 337), right under the answer
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Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Hitachi manual for the Yutaki M & Yutaki S. Check the model on the data plate before you order parts.

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